  //测量空间直线距离 
  /******************************************* */
  const measureLineSpace = (viewer,Cesium)=> {
    // 取消双击事件-追踪该位置
    viewer.cesiumWidget.screenSpaceEventHandler.removeInputAction(Cesium.ScreenSpaceEventType.LEFT_DOUBLE_CLICK);
    
    let handler = new Cesium.ScreenSpaceEventHandler(viewer.scene._imageryLayerCollection);
    var positions = [];
    var poly = null;
    // var tooltip = document.getElementById("toolTip");
    var distance = 0;
    var cartesian = null;
    var floatingPoint;
    // tooltip.style.display = "block";

    handler.setInputAction(function (movement) {
      // tooltip.style.left = movement.endPosition.x + 3 + "px";
      // tooltip.style.top = movement.endPosition.y - 25 + "px";
      // tooltip.innerHTML = '<p>单击开始，右击结束</p>';
      // cartesian = viewer.scene.pickPosition(movement.endPosition);
      let ray = viewer.camera.getPickRay(movement.endPosition);
      cartesian = viewer.scene.globe.pick(ray, viewer.scene);
      //cartesian = viewer.scene.camera.pickEllipsoid(movement.endPosition, viewer.scene.globe.ellipsoid);
      if (positions.length >= 2) {
        if (!Cesium.defined(poly)) {
          poly = new PolyLinePrimitive(positions);
        } else {
          positions.pop();
          // cartesian.y += (1 + Math.random());
          positions.push(cartesian);
        }
        distance = getSpaceDistance(positions);
        // console.log("distance: " + distance);
        // tooltip.innerHTML='<p>'+distance+'米</p>';
      }
    }, Cesium.ScreenSpaceEventType.MOUSE_MOVE);

    handler.setInputAction(function (movement) {
      // tooltip.style.display = "none";
      // cartesian = viewer.scene.camera.pickEllipsoid(movement.position, viewer.scene.globe.ellipsoid);
      // cartesian = viewer.scene.pickPosition(movement.position);
      let ray = viewer.camera.getPickRay(movement.position);
      cartesian = viewer.scene.globe.pick(ray, viewer.scene);
      if (positions.length == 0) {
        positions.push(cartesian.clone());
      }
      positions.push(cartesian);
      //在三维场景中添加Label
      //   var cartographic = Cesium.Cartographic.fromCartesian(cartesian);
      var textDisance = distance==0?'': (distance*0.001).toFixed(2) + " km";
      // console.log(textDisance + ",lng:" + cartographic.longitude/Math.PI*180.0);
      floatingPoint = viewer.entities.add({
        name: '空间直线距离',
        // position: Cesium.Cartesian3.fromDegrees(cartographic.longitude / Math.PI * 180, cartographic.latitude / Math.PI * 180,cartographic.height),
        position: positions[positions.length - 1],
        point: {
          pixelSize: 10,
          color: Cesium.Color.fromCssColorString('#1779F8'),
          outlineColor: Cesium.Color.WHITE,
          outlineWidth: 2,
        },
        label: {
          text: textDisance,
          font: '18px Helvetica',
          fillColor:  Cesium.Color.WHITE,
          style: Cesium.LabelStyle.FILL,
          showBackground:true,
          backgroundColor:Cesium.Color.fromCssColorString('#262D35'),
          verticalOrigin: Cesium.VerticalOrigin.CENTER,
          pixelOffset: new Cesium.Cartesian2(40, -20),
        }
      });
    }, Cesium.ScreenSpaceEventType.LEFT_CLICK);

    handler.setInputAction(function (movement) {
      handler.destroy(); //关闭事件句柄
      positions.pop(); //最后一个点无效
      // viewer.entities.remove(floatingPoint);
      // tooltip.style.display = "none";

    }, Cesium.ScreenSpaceEventType.RIGHT_CLICK);

    var PolyLinePrimitive = (function () {
      function _(positions) {
        this.options = {
          name: '直线测距,右键取消',
          polyline: {
            show: true,
            positions: [],
            material: Cesium.Color.fromCssColorString('#11CF8F'),
            width: 4,
            clampToGround: true
          }
        };
        this.positions = positions;
        this._init();
      }

      _.prototype._init = function () {
        var _self = this;
        var _update = function () {
          return _self.positions;
        };
        //实时更新polyline.positions
        this.options.polyline.positions = new Cesium.CallbackProperty(_update, false);
        viewer.entities.add(this.options);
      };

      return _;
    })();

    //空间两点距离计算函数
    function getSpaceDistance(positions) {
      var distance = 0;
      for (var i = 0; i < positions.length - 1; i++) {

        var point1cartographic = Cesium.Cartographic.fromCartesian(positions[i]);
        var point2cartographic = Cesium.Cartographic.fromCartesian(positions[i + 1]);
        /**根据经纬度计算出距离**/
        var geodesic = new Cesium.EllipsoidGeodesic();
        geodesic.setEndPoints(point1cartographic, point2cartographic);
        var s = geodesic.surfaceDistance;
        //console.log(Math.sqrt(Math.pow(distance, 2) + Math.pow(endheight, 2)));
        //返回两点之间的距离
        s = Math.sqrt(Math.pow(s, 2) + Math.pow(point2cartographic.height - point1cartographic.height, 2));
        distance = distance + s;
      }
      return distance.toFixed(2);
    }
  }
  export default measureLineSpace